Lead-acid dinosaurs face extinction

25. May 2016

A veritable wave of hype has swept through the car industry in the wake of the Tesla. Logistics experts, however, can only raise a weary smile about this development because electrically powered industrial trucks have long been a reality in their sector. In fact, at WOMH 2016, Linde has presented a new generation of battery-driven vehicles. In the Power Systems section I had the opportunity to talk with specialists who explained the lithium-ion technology.

Compared to conventional wet-cell technologies, lithium-ion batteries offer several striking advantages. The main argument in their favour is the charging technology. While lead-acid batteries require “some employees to go to work especially on weekends to exchange and charge the batteries” – according to Christoph Englert, product manager for electric forklifts – that is no longer necessary with the new technology. The trucks can be charged at any time and in a significantly shorter period; charging can even be done for short periods in-between. Time-consuming battery changes become a thing of the past. In addition, there is no longer any need for a special charging room with an appropriate ventilation system. Space is expensive, and this cost can now be saved.

One thing became very clear during WOMH: customers and dealers unanimously agreed that sooner or later lead-acid batteries will be replaced by more modern lithium-ion ones. And at Linde, following the new technology’s successful entry into the warehouse technology sector, it is now also being introduced in counterbalance lift trucks.

However, Linde has also undertaken a great deal of development work in the fields of battery management and safety. Its employees were proud to be able to emphasise just how many safety features have been integrated – ranging from protection against overcharging and overheating to deep discharge protection.

Let’s look at another example of what the technology offers: when a truck rolls down a slope, it switches over to energy recovery. In other words, the battery is charged. However, if the charge level is already at 100%, the battery would be overcharged and suffer damage as a result. The engineers have integrated overcharge protection to prevent that, explains Christoph Englert. Metal strips have been built in the battery housing that absorb surplus energy and then dissipate it as heat energy when there is a danger of overcharging.

Linde has even patented this system. The company also came up with a new idea for preventing deep discharge. When the battery charge falls to 10%, the vehicle is limited to creep velocity. And at 2% charge the forklift is completely switched off to be able to move the truck to the next charging station in standby mode. After all, pushing just isn’t possible.

Let’s look at safety. Everyone has heard of the exploding batteries that have blown up in the faces of mobile phone users. The batteries in hoverboards from the Far East are also said to frequently go up in smoke. As already mentioned, Linde has built in a number of ingenious features to prevent the battery coming to harm. But what happens in a crash? Won’t the battery explode? I hope you will still be able to see the crash-test video that was shown to visitors at WOMH. An 8-tonne IC forklift smashes into an electric lift truck at 20 km/h with the fork arm in front going straight into the side. And what happens? Nothing! Because the battery is encased in centimetres-thick steel (2.5 cm!), the battery cell is at most slight dented, but definitely not pierced. And that is probably what we would expect of a Linde forklift – it has to be robust and safe.

E16 EVO

While Tesla is still scoring points for developing early demand for electric vehicles, the second generation of electric forklifts is already entering warehouses.